LCG – AA review 1 Simulation LCG/AA review Sept 2006

LCG – AA review 2 Generators (I) GENSER used actively by ATLAS & LHCb, CMS. The recommendations of last year review addressed Granular packaging of GENSER, modular way for downloading also individual packages HepMC support considerably improved Concerns about GENSER contents Many versions, platforms. Does not seem to have a clear policy for keeping/dropping a version Fortran code is quite prevalent Not yet a concern, but something to keep in mind Development/tuning of C++ generators should be encouraged It is essential to have the code repository mirrored at CERN

LCG – AA review 3 Generators (II) Change of project leader is an opportunity to review the communication channels between authors and the project More sharing of information and clarification of mandate is encouraged Development of a validation suite is recommended MCDB is found to be very useful to CMS and CMS is switching to this

LCG – AA review 4 Physics Validation Good collaborations with experiments for various physics validation studies have been established Various test beam setups The ongoing activities in LHC test beam analysis are supported Big amount of work has been performed in order to bring FLUKA into the game The application for FLUKA-G4-test beam data comparison has been developed No results yet though, they are highly expected Extensions of FLUKA tests are also recommended Archiving test beam data (distributions) for future validation will be very useful. However, one has to take care of effect of beam background and other systematic effects

LCG – AA review 5 GEANT4 is the main simulation engine for three LHC experiments, it is being used in large scale productions and as well as in various validations (test beams) Experiments are often using their own installations for flexibility and validation Hadronic shower shape is still an issue, although continuous efforts are made by G4 team to improve the situation Performance issues: New multiple scattering introduced serious performance penalties good performance and good physics are both important Arithmetic instability is greatly reduced - it needs to be further reduced. Feedback from experiments is critical GEANT4

LCG – AA review 6 The legal situation with FLUKA has been resolved. The installation/deployment aspects are also improving Has become the main tool for radiation studies Agreements with some experimental data are impressive Performance aspects when simulating complex detectors ? If becomes popular among experiments more efforts should put on deployment/training FLUKA

LCG – AA review 7 The simulation framework work packages mainly have been used internally within Simulation project (Physics Validation) Although the components of the Simulation Framework are generic and ready for wide usage GDML has reached a level of maturity and provides very important functionalities for various validation studies Can guarantee geometry consistency across application boundaries, even using different simulation engines (FLUGG) The geometry persistency with ROOT has been implemented and is ready to use. It can be also of high level interest for applications with rather long initialization time for complex geometries Simulation Framework (I)

LCG – AA review 8 HepMC related studies resulted to an example ‘MCTruthManager’ which can be added to G4 Most of the milestones in the project have been accomplished. Only few short-term activities are ongoing Simulation Framework (II)